An efficiency and a sound quality of an audio signal may be maximized by using different encoding methods depending on a property of an input signal. As an example, when a CELP based voice and audio encoding device is applied to a signal, such as a voice, a high encoding efficiency may be provided, and when a transform based audio coder is applied to an audio signal, such as a music, a high sound quality and a high compression efficiency may be provided.
Accordingly, a signal that is similar to a voice may be encoded by using a voice encoding device and a signal that has a property of music may be encoded by using an audio encoding device. A unified encoding device may include an input signal property analyzing device to analyze a property of an input signal and may select and switch an encoding device based on the analyzed property of the signal.
Here, to improve an encoding efficiency of the unified voice and audio encoding device, there is need of a technology that is capable of encoding in a real domain and also in a complex domain.